Field of the Invention
In my copending application, Ser. No. 557,612, now U.S. Pat. No. 4,005,932, photogrammetric apparatus is disclosed which utilizes a flexible platen to provide an absolute stereo image for photographic and other purposes. A multiplicity of points on the flexible platen are vertically adjustable by adjustment means to provide a three-dimensional photographic surface to enable relief distortion from aerial photographs to be eliminated in photographs which are taken of the adjusted flexible platen. If color film is used, such as Echtachrome-X, an orthostereoscopic slide or print results. The orthostereoscopic photo comprises a stereoscopic image which constitutes a geometrically accurate model having no distortion of perspective and enabling the two visually fused images to produce a unitary spatial picture.
In a regular or uncorrected anaglyphic, when projected or printed, the image is formed at approximately 1/2 plane of the spatial model. This is to aid in viewing so that the two separate images are separated as evenly as possible. However, with the orthostereoscopic image, there is no separated image as one image is directly over another to form one constant image therefrom. The spatial image may be adjusted to the plan of view and accordingly, the spatial image may be at its lowest or highest plane of view.
The subject invention is directed to utilizing the orthostereoscopic slide by the method and apparatus disclosed herein to provide a means for contour plotting. While the primary use of contour plotting is for mapmaking, the photogrammetric principles disclosed herein may also be utilized in numerous other fields to solve problems of mensuration requiring both absolute and relative determinations of size, shape, depth, height, and location of objects in their environment.
Heretofore, conventional contour plotting, techniques of which are fully disclosed in volumes 1 and 2 of the Manual of Photogrammetry published by the American Society of Photogrammetry, was carried out by utilizing standard table tracing with conventional platens and tracing apparatus. Accordingly, the prior art does not disclose a means of producing contour maps from orthostereoscopic slides, the latter which may be developed by following the teachings of my copending application, Ser. No. 557,612, now U.S. Pat. No. 4,005,932.